Q-jet and Holley

Adger Smith · 12-18-2011, 04:38 PM

Yes, N/S = Needle and Seat
Put a stock curved bottom Air filter on the Q-jet to test it. Use o2's instead of the hat to tune. Don't run the fuel pressure too high. The q-jets I've delt with don't like high fuel pressure because of the float. The bigger the N/S the harder it is for the float to overcome pressure (W/added N/S area)and maintain proper float level. Thanks, No thunder here, Ed :~0
Sorry didn't see the temps. Look how the numbers changed. You had cool get hotter and hot get cooler and I looked at it the temps a little differently. Actual firing order.
Cyl # 1 #8 #4 #3
-1 -60 -55 +11

Cyl #6 #5 #7 #2
+23 -18 -55 -48
Notice 3 & 6 got hotter. Is it a coincidence they are in the center of the engine and on opposite banks? Look at the manifold design.
With just a carb change you were down on power and the temp changes were significant
leads me to believe there is an air / fuel problems. It is either the hat distrubing the air or the carb is way off.

12-18-2011, 04:38 PM	#9
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Q-jet and Holley Yes, N/S = Needle and Seat Put a stock curved bottom Air filter on the Q-jet to test it. Use o2's instead of the hat to tune. Don't run the fuel pressure too high. The q-jets I've delt with don't like high fuel pressure because of the float. The bigger the N/S the harder it is for the float to overcome pressure (W/added N/S area)and maintain proper float level. Thanks, No thunder here, Ed :~0 Sorry didn't see the temps. Look how the numbers changed. You had cool get hotter and hot get cooler and I looked at it the temps a little differently. Actual firing order. Cyl # 1 #8 #4 #3 -1 -60 -55 +11 Cyl #6 #5 #7 #2 +23 -18 -55 -48 Notice 3 & 6 got hotter. Is it a coincidence they are in the center of the engine and on opposite banks? Look at the manifold design. With just a carb change you were down on power and the temp changes were significant leads me to believe there is an air / fuel problems. It is either the hat distrubing the air or the carb is way off. __________________ Adger Smith (Former SS) Last edited by Adger Smith; 12-18-2011 at 05:25 PM. Reason: add on :~)